package com.zhongxi.guoyuan.utils;

import android.util.Log;

import java.security.Key;
import java.security.spec.AlgorithmParameterSpec;

import javax.crypto.Cipher;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
import javax.crypto.spec.IvParameterSpec;

/**
 * Created by Administrator on 2016/11/12.
 */

public class DesTool {

    public static final String ALGORITHM_DES = "DES/CBC/PKCS5Padding";

    /**
     * 获取key和byte[]向量
     * @param sourceStr
     * @param data
     * @return
     * @throws Exception
     */
    public static String split( String sourceStr, String data) throws Exception {
        String sureStr = sourceStr.substring(16, sourceStr.length());
        String before = sureStr.substring(0,8);
        String after = sureStr.substring(8,16);
        Log.i("now","before="+before);
        Log.i("now","after="+before);
        return encode(after, data, before.getBytes());
    }

    /**
     * 获取key和byte[]向量
     * @param sourceStr
     * @param data
     * @return
     * @throws Exception
     */
    public static String splitdecode( String sourceStr, String data) throws Exception {
        String sureStr = sourceStr.substring(16, sourceStr.length());
        String before = sureStr.substring(0,8);
        String after = sureStr.substring(8,16);
        return decodeValue(after.getBytes(), data, before.getBytes());
    }

    /**
     * 加密
     * @param data 待加密字符串
     * @param key 加密私钥，长度不能够小于8位
     * @return 加密后的字节数组，一般结合Base64编码使用
     */
    public static String encode(String key, String data, byte[] ivbyte) throws Exception {
        return encode(key, data.getBytes(), ivbyte);
    }

    /**
     * 加密
     * @param data 待加密字符串
     * @param key 加密私钥，长度不能够小于8位
     * @return 加密后的字节数组，一般结合Base64编码使用
     */
    public static String encode(String key, byte[] data, byte[] ivbyte) throws Exception {
        try {
//            byte[] ivbyte = { 1, 2, 3, 4, 5, 6, 7, 8 };
            DESKeySpec dks = new DESKeySpec(key.getBytes());

            SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
            // key的长度不能够小于8位字节
            Key secretKey = keyFactory.generateSecret(dks);
            Cipher cipher = Cipher.getInstance(ALGORITHM_DES);
            IvParameterSpec iv = new IvParameterSpec(ivbyte);
            AlgorithmParameterSpec paramSpec = iv;
            cipher.init(Cipher.ENCRYPT_MODE, secretKey, paramSpec);

            byte[] bytes = cipher.doFinal(data);

            return Base64.encode(bytes);
        } catch (Exception e) {
            throw new Exception(e);
        }
    }

    /**
     * 解密
     * @param data 待解密字符串
     * @param key 解密私钥，长度不能够小于8位
     * @return 解密后的字节数组
     * @throws Exception 异常
     */
    public static byte[] decode(byte[] key, String data, byte[] ivbyte) throws Exception {
        try {
            DESKeySpec dks = new DESKeySpec(key);
            SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
            // key的长度不能够小于8位字节
            Key secretKey = keyFactory.generateSecret(dks);
            Cipher cipher = Cipher.getInstance("DES/CBC/NoPadding");
            IvParameterSpec iv = new IvParameterSpec(ivbyte);
            AlgorithmParameterSpec paramSpec = iv;
            cipher.init(Cipher.DECRYPT_MODE, secretKey, paramSpec);
            byte[] a = Base64.decode(data);
            return cipher.doFinal(a);
        } catch (Exception e) {
            throw new Exception(e);
        }
    }

    /**
     * 获取编码后的值
     *
     * @param key
     * @param data
     * @param ivbyte
     * @return
     * @throws Exception
     */
    public static String decodeValue(byte[] key, String data, byte[] ivbyte) {
        byte[] datas;
        String value = null;
        try {
            if (System.getProperty("os.name") != null
                    && (System.getProperty("os.name").equalsIgnoreCase("sunos") || System
                    .getProperty("os.name").equalsIgnoreCase("linux"))) {
                datas = decode(key, data,ivbyte);
            } else {
                datas = decode(key, data,ivbyte);
            }
            value = new String(datas);
        } catch (Exception e) {
            value = "";
        }
        return value;
    }

}
